Fixed compressor vane assemblies utilized in current production large military and civil powerplants are typically mounted to an intermediate structure which is then tied to the compressor case wall. These case-tied designs are utilized in an attempt to isolate the flowpath endwall from case distortions brought on from carcass bending loads and the asymmetric radial growth of a horizontally split compressor case. The case-tied designs also attempt to control outer endwall displacement in line with radial blade tip growth in order to minimize tip clearance throughout the flight envelope. After having been properly matured, these designs have generally provided acceptable performance characteristics.
The compressor vane assembly designs employed in current practice are, however, generally very complex. They rely on individual or segmented vane assemblies, full ring or split intermediate structures, a multitude of seal elements and a separate outer case assembly. This complex architecture has proven to be heavy and costly. In addition, the number of interfaces in this complex architecture results in multiple potential leak paths at the outer endwall which are difficult to seal. Even a well sealed design can degrade with time as seal interfaces wear. The multiple leak paths can result in recirculation at the outer endwall resulting in operability issues. In addition to high initial cost, the case-tied architecture results in high maintenance costs as wear at retaining hooks and seal interfaces must be addressed.
Accordingly there is a need for a unique and inventive apparatus of a compressor case and vane system.